Energy counters are a kind of counter that a player may have. They’re not associated with specific permanents. (Other kinds of counters that players may have include poison and experience.)

2/9/2017

Keep careful track of how many energy counters each player has. You may do so by keeping a running count on paper, by using a die, or by any other clear and mutually agreeable method.

2/9/2017

If an effect says you get one or more , you get that many energy counters. To pay one or more , you lose that many energy counters. Any effects that interact with counters a player gets, has, or loses can interact with energy counters.